I had plenty of storage on my old bike, pretty much a 20inch deep storage bucket under the seat so I carried loads of stuff. It sounds overboard but as it was my only form of transport and not exactly new from the showroom I wanted to be able to fix things at the roadside whenever possible. Most of the things I carried were tailored to the issues I'd come across with that bike which was mainly electrical faults, allan keys, selection of sockets and a ratchet, multi screwdriver, stubby hammer, stanley knife, electrical tape, small spool of garden wire, a tin of gungum (I had a crack in my header pipe that I kept patching every now and then) little bottle of wd40, mini tube of vaseline, pliers, mole grip (really useful if clutch cable end snaps) spare fuses, a square of sandpaper, puncture repair kit, spare spark plug. Think thats about it